Irregularities in the pigmentation of the skin have always been considered unsightly, and for some considerable time various means have been proposed to remedy this.
These defects appear most often in the form of hyperpigmentation blemishes, which may take diverse forms: freckles, chloasma of hormonal origin, senile lentigo located mainly on the hands, hyperpigmentation related to scars or resulting from a photosensitizing agent, and the like.
A most diverse range of approaches has been proposed for removing these blemishes, and whitening the skin, imparting a uniform coloration thereto. The use of numerous substances of animal or mineral origin, as well as of a large variety of plants and substances of vegetable origin, has been recommended for this purpose. The publication of SCARPA and GUERCI [Journal of Ethnopharmacology, 19 17-66 (1987)] reveals the diversity of the preparations proposed.
However, a very small number of the formulations thus proposed have shown any real proof of their effectiveness. At the present time, very few substances are known which have a real depigmenting effect, and among these substances the majority exhibit annoying, or even harmful, side effects.
For example, certain preparations based on mercury salts, although endowed with a real power for lightening the skin, present real danger, because the transcutaneously absorbed mercury may cause serious poisoning.
The majority of the depigmenting preparations currently available commercially contain hydroquinone as the active ingredient. These preparations are, however, not without disadvantages. They are in fact very difficult to handle: their application must effectively be strictly limited to the regions to be depigmented, and the amount used must be carefully dosed. These disadvantages are particularly important for subjects of dark skin, for whom there is a risk of new blemishes appearing resulting from a non-uniform depigmentation. In addition, hydroquinone is poorly tolerated by many people, in whom it provokes skin irritations.
Among the innumerable active principles of vegetable origin, or extracted from plants, to which a depigmenting action has been attributed, only one is effectively used in cosmetology: this is an extract of the common yarrow, whose activity is thought to arise from the presence of luteolin and its heterosides.
The Inventor has undertaken research with the aim of discovering other substances which regulate pigmentation without, however, exhibiting the disadvantages of the substances currently used.
It is in fact desirable to have available substances which remove pigmentation blemishes without, however, provoking a general whitening of the skin or else an excessive depigmentation of the regions treated. It is in addition necessary for these active principles to be well tolerated and, in particular, not to provoke irritation.